The present invention relates to a sheet cutting device enable of cutting simultaneously a plurality of sheets, and in particular, to a sheet cutting device which can be installed in an image forming system, such as a copy machine, a printer, a facsimile, and a compound apparatus which includes more than two functions of the above functions, and to a sheet post-processing device incorporating the sheet cutting device described above.
As the sheet post-processing device which is installed in a system of the image forming apparatus, apparatuses have been developed which produce booklets via bundling a plurality of sheets. In most of the sheet post-processing devices, the bundles of sheets are folded at their central sections, then bound at the central sections, after which, facing sections to the bound sections, that is, the edges opposite the bound edges are cut by the sheet cutting device, resulting in a uniformly edged booklet.
Since the sheet cutting device to be installed in the sheet post-processing device is structured as part of the image forming apparatus installed in copy centers or offices, it must be small-sized, as well as working with low power consumption, and further, it is necessary that the function to produce uniformly edged booklets is always maintained. If the cut edges are uneven, or uncut portions remain, the booklet cannot be opened smoothly, which is of course a major problem.
On the other hand, a sheet cutting apparatus used in the production process of a great number of the same booklets, such as printed matter, is a large-scale operation and driven by great electric power, accordingly, such sheet cutting apparatus need only be good enough to exhibit high cutting performance. However, concerning the sheet cutting device used as a part of the image forming apparatus, the essential condition is that the device is operable with small electric power, and is small in overall size. Therefore, design in ingenuity is necessary to perform functions beyond the large-scale sheet cutting apparatus.
Japanese Unexamined Patent Publication No. 2003-136471 (hereinafter referred to as the Patent Document) discloses a sheet cutting device wherein the sheets are trimmed by a cutter which is pressed against the sheet surface at a slant, as the sheet cutting device which can be used in a business machine.
The sheet cutting device disclosed in the Patent Document cuts the sheets with a cutter strongly pressed against the sheet, while the bundle of sheets is secured under high pressure. This sheet cutting device takes a few seconds to a few ten seconds for one process of cutting a bundle of a few ten or a few thousand sheets, and during this process, the bundle of the sheets are secured as it is at the cutting position.
In order to increase working efficiencies of the sheet post-processing device incorporating the sheet cutting device, as well as the image forming system incorporating the sheet post-processing device, it is essential that the time interval for securing the bundle of sheets at the cutting position is reduced as far as possible. Further, according to the structure described in the Patent Document, the pressing member also works as a receiving section of the cutter blade. Therefore, when the cutter blade is moved in the slanted direction for cutting the sheets, the cutter blade breaks into the pressing member, while moving in the slanted direction. Still further, after cutting, when the cutter blade is released from the pressing member, a large noise is produced by friction.